A comedy-drama starring Hugh Grant as Will, a rich, child-free and irresponsible Londoner in his thirties who, in search of available women, invents an imaginary son and starts attending single parent meetings. As a result of one of his liaisons, he meets Marcus, an odd 12-year-old boy with problems at school. Gradually, Will and Marcus become friends, and as Will teaches Marcus how to be a cool kid, Marcus helps Will to finally grow up.